I've heard from someone you can dial a code, when you do so you will see a menu where you can shut down the 4g and you than use 3g like normal phones. When you enable gsm only the phone is running on gprs, am i right? Someone else heard about this?
Things like this would, in most cases that I am aware of, be done through rooting your phone and modifying the radios or the ROM. Technically though, the Sensation 4G uses HSPA+ which is an advanced form of 3G technologies. Unfortunately it seems that the standard has a similar effect as LTE does on phones, causing battery drain that is less than what one would hope for.
I am currently on the search for an application that will force 3G usage until it sees that their is something to download, and then switch to 4G. In most cases, this would seem like a logical way to use the phone. 4G is fast and cool, but its not the best primary antenna usage just yet. I know we are paying for 4G speeds and stuff, but most people wont notice the difference in speeds if they have a program to use 3G antennas for things under a certain file size. I know my emails dont need to be on my phone a half second faster, as long as im getting them within a minute of when they show up on the server, im happy.
EDIT: I will post information about my findings if I find any type of application like the one I mentioned above